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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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Conference on Nuclear Training and Education: A Biennial International Forum (CONTE 2025)
February 3–6, 2025
Amelia Island, FL|Omni Amelia Island Resort
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The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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ANS standard updated for determining meteorological information at nuclear facilities
Following approval in October from the American National Standards Institute, ANSI/ANS-3.11-2024, Determining Meteorological Information at Nuclear Facilities, was published in late November. This standard provides criteria for gathering, assembling, processing, storing, and disseminating meteorological information at commercial nuclear power plants, U.S. Department of Energy/National Nuclear Security Administration nuclear facilities, and other national or international nuclear facilities.
Bo Shi, Bojan Petrovic
Nuclear Science and Engineering | Volume 172 | Number 2 | October 2012 | Pages 138-150
Technical Paper | doi.org/10.13182/NSE11-19
Articles are hosted by Taylor and Francis Online.
The Monte Carlo method is widely used to compute the fundamental eigenfunction and eigenvalue for nuclear systems. However, the standard power iteration method computes only the fundamental eigenmode, while it would be beneficial to also compute the higher eigenfunctions and eigenvalues to support the reactor transient analysis, stability analysis, and assessments of nuclear safety, as well as to enable certain source convergence acceleration techniques. Modifications to the power method have been developed that in principle can accomplish this goal, but they typically lead to unphysical positive and negative particles requiring a procedure to compute the net-weight deposition. In this paper, we present a new mechanism that enables the Monte Carlo procedure, with certain modifications, to compute the second eigenfunction and eigenvalue for one-dimensional (1-D) problems. The method could in principle be extended to higher harmonics and general geometries. The results from numerical examples, including a 1-D, two-group, multiregion example, are consistent with reference results. Moreover, the extra computational cost of this method is of the same order of magnitude as the conventional Monte Carlo simulations. This method can be applied solely to solve for the high eigenmodes, or implemented as a part of a net-weight computation mechanism when negative particles are present in the modified power iteration method.